Interconversion of Composition Measures

Given the solution composition in mass percent, it is easy to compute the mole fractions of solute and solvent and the molal concentration of solute.

Example 1

What are the mole fractions and molal concentrations in a 10% by weight solution of CH₃OH in water? We first compute the number of moles of CH₃OH and water:

The total number of moles is 5.33 and the mole fractions are:

The molal concentrations of CH₃OH is computed from the number of moles and the mass of H₂O.

Molar concentrations involve the volume of the solution and to get this from the mass, we need the density.

Example 2

Given that the density of 10.0% aqueous NaCl is 1.071 g/cm³, what is the molar concentrations of Na⁺ and Cl^-?

Two approaches are possible. (1) We know how many moles of NaCl are contained in 100 g of solution. Thus we have

(2) One liter of solution weighs 1071 g and contains 107.1 g NaCl/L; converting to moles, we have [NaCl] = [Na⁺] = [Cl^-] = 1.83 mol/

مواضيع ذات صلة

نظام استخلاص الجزئيات البسيطة

اختيار الطور الجديد وعدد مرات الاستخلاص

ميكانيكية الاستخلاص

طبيعة الصنف المستخلص

الاستخلاص بالمذيب

امتصاص الشعاع الكهرومغناطيسي وطيف الامتصاص

الطرق الكيميائية الطيفية في التحليل.

طبيعة الكيمياء التحليلية

التحليل بالحقن الجرياني المتقطع Batch flow injection analysis

الحقن الجرياني متعدد التخفيف Multi-commutation in FIA

التحليل بالحقن المتعاقب Sequential Injection Analysis

التحليل بالجريان المتقطع Segment Flow Analysis